Writing Down Obsolete Inventory: A Small Business Guide to Lower of Cost or Net Realizable Value

Look at your balance sheet. That inventory line — $85,000, $240,000, whatever it shows — feels reassuring. It's an asset, after all. But walk into your warehouse and look at the back shelf. The SKU you over-ordered eighteen months ago. The parts for a product you discontinued. The fabric in last year's color that nobody wants at full price anymore. If you had to turn that pile into cash tomorrow, would you get anything close to what you paid?

For many small businesses, the honest answer is no. And under GAAP, you are not allowed to pretend otherwise.

Carrying obsolete inventory at full cost overstates your assets, inflates your profit, and can lead to a nasty surprise at year-end when your accountant — or your bank — asks why your gross margin collapsed after a physical count. Learning when and how to write inventory down to its real value is one of the most important bookkeeping disciplines for any business that holds stock, whether you sell on Shopify, supply contractors, or run a small manufacturing shop.

Why Your Inventory Balance Is Probably Overstated​

Inventory feels different from other assets. You bought it, you own it, you paid real money for it. It sits on the shelf. The instinct is to keep it on the books at cost until you sell it or throw it away.

Accounting doesn't work that way. The core principle behind inventory valuation is conservatism: don't overstate what you own. If the value of your inventory has fallen below what you paid — because it is damaged, obsolete, slow-moving, or simply worth less in today's market — you have already incurred an economic loss. GAAP requires you to recognize it now, not when you finally mark it down or dumpster it.

The consequences of not doing this compound:

• Your balance sheet looks stronger than it is, which misleads you, your lender, and any potential investor.
• Your cost of goods sold stays artificially low, so gross profit looks better than reality. You make pricing and purchasing decisions on bad data.
• When you eventually sell at a deep discount or write off the stock, you take a sudden, large hit that should have been spread out as the obsolescence became clear.
• If 40 to 60 percent of your balance sheet is inventory — common for wholesalers, retailers, and distributors — a 20 percent overstatement can wipe out your reported equity.

This isn't about being pessimistic. It's about making decisions on reality.

The Rule: Lower of Cost or Net Realizable Value​

The rule that governs this lives in ASC 330, Inventory (formerly ARB 43). For most small businesses using FIFO or average cost, the rule is straightforward: inventory must be reported at the lower of cost or net realizable value (LCNRV).

If net realizable value falls below cost, you write it down. You never write it back up under U.S. GAAP, even if the market recovers.

What Is Net Realizable Value?​

Net realizable value (NRV) is not a theoretical market price. It is the estimated amount you will actually pocket from selling the item in the ordinary course of business.

The formula is simple:

NRV = Estimated Selling Price - Estimated Costs to Complete and Sell

Costs to complete and sell include:

• Direct selling costs (shipping to customer, marketplace fees, sales commissions)
• Costs to finish the item if it is work-in-progress (labor, materials, packaging)
• Any costs to prepare it for sale (repackaging, small repairs)

You do not subtract general overhead or administrative costs. You subtract only the costs that are directly tied to getting that specific inventory out the door.

An example: You bought 500 units of a kitchen gadget at $20 each. Total cost: $10,000. The product was hot last year, but a new version launched. You can now realistically sell it only at $14 per unit, and you will pay $2 per unit in Shopify fees and shipping subsidies to move it.

NRV per unit = $14 - $2 = $12 Total NRV = 500 x $12 = $6,000 Cost = $10,000 Write-down required = $4,000

You keep $6,000 on the balance sheet. The $4,000 is a loss in the current period.

How the Comparison Works​

You apply LCNRV item by item — or by logical group where items are similar — not to the inventory total as a whole. Averaging a few obsolete SKUs into a large healthy pool to avoid a write-down is not permitted.

• If NRV is higher than cost, you do nothing. You keep it at cost.
• If NRV is lower than cost, you write it down to NRV. The difference hits the income statement.

Under the older retail or LIFO conventions you may still see "lower of cost or market" with a ceiling and floor (replacement cost bounded by NRV), but for most small businesses not on LIFO, LCNRV is the rule.

What Actually Creates Obsolete Inventory​

Obsolescence rarely arrives with an obvious alarm. It creeps in through normal business decisions:

Demand shifts. Consumer preferences change, a new model replaces yours, or a major customer stops ordering a custom part. That 12-month supply you bought to get a volume discount now looks like a 36-month supply.

Overbuying and MOQ pressure. Suppliers offer a 15 percent discount at 1,000 units. You buy 1,000 even though you sell 30 per month. Six months later, half is still there and a newer option exists.

Perishability and shelf life. Food, cosmetics, chemicals, and even certain electronics components expire or degrade. Once the best-by date passes, NRV may be zero.

Damage and quality issues. A forklift punctures a pallet, humidity warps packaging, or a batch fails QC but isn't physically scrapped. It is still counted, but its realizable value has collapsed.

Technology change. Components, firmware-linked accessories, or fashion-driven goods lose value quickly when the next version ships.

A useful test: if an SKU hasn't turned in 9 to 12 months and has no firm forward order, pull it for an NRV review. What you find there often pays for the exercise.

How to Calculate and Document NRV in Five Steps​

You don't need a Big Four valuation team to do this. You need a repeatable process you can defend to your CPA and, if relevant, to the IRS.

1. Segment your inventory​

Export your inventory detail by SKU, including quantity on hand, unit cost, and last sale date. Group by product family if you have thousands of SKUs, but keep slow movers visible — don't let aggregates hide them.

2. Flag candidates for testing​

Prioritize:

• No sales in the last 180-365 days
• Quantity on hand greater than 12 months of sales
• Known damaged, returned, or expired items
• Items tied to discontinued products

This triage focuses your effort where a write-down is most likely.

3. Gather evidence for estimated selling price​

Your estimate must be grounded in observable data, not hope. Use:

• Your own recent discounted sales of the same or similar item
• Current listed prices for the same item on your site, Amazon, or wholesale sheet — not the aspirational MSRP
• Written bids or quotes from liquidators, discount buyers, or scrap dealers
• Published price sheets from competitors for identical goods

Take screenshots, save emails, and keep a small file per flagged SKU. "We can probably still get full price" without evidence will not survive an audit.

4. Estimate costs to complete and sell​

For finished goods, this is usually selling costs: payment processing, shipping subsidies, commissions. For work-in-progress, add the remaining labor and materials to finish it into a salable form. Be realistic — if you will need to pay a marketplace an 8 percent referral fee plus $3 in outbound shipping, subtract it.

5. Compare and calculate the loss​

For each flagged item or group: NRV = Estimated Selling Price - Costs to Complete and Sell Loss per unit = Cost - NRV (if positive) Total write-down = Loss per unit x Quantity on hand

Sum the total. That sum is the amount you adjust.

A slightly larger example:

You distribute specialty coffee equipment. You have 80 units of a grinder model you bought at $320. You discontinued it when the manufacturer released Gen 2. Over the last 90 days you sold three units at $299, but only after offering free shipping that cost you $28 and paying a 3 percent card fee ($9). Your realistic selling price going forward is $299.

NRV per unit = $299 - $28 - $9 = $262 Cost per unit = $320 Loss per unit = $58 Total write-down = 80 x $58 = $4,640

That $4,640 is not a future problem. It is today's loss.

How to Book the Write-Down​

There are two accepted ways to record it. Both reduce inventory and hit the income statement in the current period. The difference is presentation.

Option A: Direct write-down (most common for small business)​

Debit the loss directly and credit inventory:

• Debit: Loss on Inventory Write-Down (or included in Cost of Goods Sold) — $4,640
• Credit: Inventory — $4,640

Many small businesses record it inside COGS so that gross margin reflects the true economics. A separate line like "Inventory write-down expense" above gross profit is more transparent if the amount is material — and your bank or investors will appreciate the visibility.

Option B: Allowance method​

Useful if you review inventory quarterly and want to show the reserve explicitly:

• Debit: Loss on Inventory Write-Down — $4,640
• Credit: Allowance for Inventory Obsolescence (a contra-asset) — $4,640

Inventory stays at gross cost on your trial balance, with the allowance as a separate offsetting line on the balance sheet. When you actually scrap or sell at a loss, you charge the allowance rather than booking a second loss.

Either way, the effect on the balance sheet and income statement is the same in the period of the write-down. Pick one method and stay consistent.

A critical rule: you don't get to skip the entry because you haven't physically disposed of the inventory. The loss is recognized when NRV falls below cost, not when you throw the items away. Scrapping later without a prior write-down just delays honesty.

What Not to Do​

• Don't bury the adjustment in "Miscellaneous expense" or net it against purchases. Keep it visible inside or immediately below gross profit.
• Don't credit accounts payable or another vendor account. This is a valuation adjustment, not a vendor return.
• Don't create a vague year-end journal entry with no SKU-level support. If you can't show your math per item, you can't defend it.

The Tax Trap: GAAP Wants It Now, the IRS Wants Proof​

Here is where many small businesses get tripped up. GAAP and tax rules both talk about writing down inventory, but they have different thresholds for when you can deduct it.

For book purposes (GAAP): You write down as soon as NRV falls below cost, based on a reasonable estimate.

For tax purposes: The IRS is stricter. Under Regulation 1.471-2(c), you can value inventory at the lower of cost or market, but market has to be demonstrably lower, and you need objective evidence — not just a judgment that it is slow-moving.

In practice, the IRS will respect a write-down for tax purposes when:

• The goods are subnormal — damaged, defective, shopworn, obsolete, or otherwise unsalable at normal prices — and you can show that.
• Or the goods are normal but you can demonstrate that the market price has declined and you would have to sell below cost in the normal course, supported by recent actual sales, bona fide price lists, or firm offers.

An allowance for "general obsolescence" or a blanket reserve like "we reserve 10 percent just in case" is generally not deductible for tax. Neither is carrying an expected decline that hasn't yet been realized through lower prices or firm offers. The tax deduction typically comes when you:

• Establish a lower replacement cost through actual purchase offers or published market declines,
• Offer the goods at a lower price and show they are offered at that price (with price lists, website listings, written liquidator bids), or
• Actually dispose of the goods, at which point the loss is recognized through higher COGS.

This creates a common temporary book-tax difference: you book the $4,640 write-down now for GAAP, but you may not deduct it on this year's federal return until you meet the tax standard. You will track this difference — your CPA will handle it with a deferred tax note if you are accrual basis — but the book entry is still essential. Your management financials and lender reporting should reflect economic reality even when the tax deduction lags by a quarter or two.

If you use the cash method, inventory still matters. You cannot deduct inventory purchases outright. You capitalize them and deduct them through COGS as you sell. A write-down doesn't create a "more immediate" deduction than that principle allows; it just ensures your ending inventory isn't overstated, which would otherwise depress COGS and inflate taxable income in the wrong direction.

Documentation that helps both GAAP and the IRS:

• SKU-level NRV worksheets (cost, estimated price, costs to sell, NRV, loss)
• Dated screenshots of current selling prices or discounted listings
• Liquidator or scrap bids in writing
• Notes on why the item is subnormal (damage photos, manufacturer discontinuation notice, engineering memo)
• Management approval of the write-down with a date

The stronger the paper trail, the easier it is to defend a tax write-down in the same year as the book write-down.

Why Small Businesses Wait Too Long — and How to Fix It​

Most obsolescence write-downs are not hard to calculate. They are hard to notice in a busy operation where no one owns the inventory ledger.

Common failure patterns:

No one ages the inventory. Without a report of last-sale date and months of supply on hand, slow movers sit invisible inside a total inventory balance. Pull an inventory aging at least quarterly.

Physical counts are annual. If you count once a year, you discover obsolescence once a year — and usually after year-end, when the adjustment hurts most. Move high-value or high-risk categories to cycle counts. Count A-items monthly, B-items quarterly.

Purchasing and accounting don't talk. Purchasing gets the volume discount, accounting records the receipt, and no one loops back to ask "did this actually sell through?" Require a quick post-mortem when quantity on hand exceeds forecast by more than 50 percent.

The sunk-cost trap. "We paid $320, we can't write it down to $262, we'll wait until we get full price." Meanwhile storage costs accumulate, cash stays trapped, and the market falls further.

A practical cadence that works for a 5- to 50-person company:

• Monthly: Review inventory aging and DIO (days inventory outstanding). DIO = (Average Inventory / COGS) x 365. If DIO is creeping up while sales are flat, something is sticking.
• Quarterly: Run the NRV test on every item flagged as no sales in 180 days, or months-on-hand above 12. Book write-downs quarterly, not as a year-end surprise.
• Annually: Do a formal obsolescence reserve review before your tax return or review, with signed documentation. If you have a bank line secured by inventory, send the lender the clean inventory report — they will respect the discipline and it protects your borrowing base from a sudden field-exam adjustment.
• Ongoing: Tag every purchase order over a threshold with an expected sell-through date. If an item misses that date by 90 days, it automatically enters the NRV review.

Treating inventory as a live asset class — not a number you true up in December — also makes insurance, lending, and pricing conversations easier. You actually know what you own.

Can You Reverse a Write-Down Later?​

In short: not under U.S. GAAP. Once you write inventory down to NRV, you establish a new cost basis. If the market recovers and the item regains value, you do not write it back up. You recognize the benefit later, in effect, through a higher margin when you sell — you sell inventory you carry at $262 for, say, $299, and the $37 spread flows through COGS favorably at sale.

This "no reversal" rule is a frequent source of confusion for business owners who follow IFRS companies, where IAS 2 does permit reversals of inventory write-downs when circumstances change. If you report under U.S. GAAP — as almost all small private companies in the United States do — assume the write-down is one-way.

That irreversibility is actually a reason to be timely and precise, not a reason to delay. Waiting until the value is unambiguously zero forces you to take a larger hit later that could have been recognized gradually and managed.

Your Action Checklist This Quarter​

1. Export your inventory detail with quantity, unit cost, and last-sale date. Calculate months of supply for each SKU.

2. Flag every SKU with no sales in 180 days, or with quantity covering more than 12 months of forward sales, plus anything you know is damaged or discontinued.

3. For each flagged SKU, determine NRV: gather at least one piece of observable evidence for the selling price (recent invoice at discount, current listing, liquidator bid) and subtract the direct costs to sell.

4. Prepare a one-page NRV worksheet per SKU or product family. Get owner or controller sign-off and keep the evidence file.

5. Book the write-down in your accounting system this period — debit write-down expense (or COGS) and credit inventory or the obsolescence allowance. Don't defer it to year-end.

6. Discuss tax deductibility with your CPA. Bring the worksheets and the price evidence. You may have a book-tax difference to track even if the book entry is clearly required.

7. Act on the source. Discount to move slow product, bundle it, return it to the vendor if the contract allows, or donate qualifying product for a charitable deduction rather than paying another year of warehousing on dead stock. Clearing the shelf at 60 cents on the dollar and redeploying the cash is usually better than carrying a $10,000 fiction on the balance sheet.

8. Put a quarterly reminder on the calendar to repeat steps 1 through 5. Obsolescence is not a one-time event.

Simplify Your Financial Management​

Staying on top of inventory write-downs is part of a bigger habit: keeping your books close to reality so you can make better decisions month to month, not just at tax time. When your inventory, margin, and cash are all tied together in transparent, version-controlled records, you spot a deteriorating gross margin or a bloated stock level while there is still time to course-correct.

Beancount.io gives you plain-text accounting that is transparent, version-controlled, and AI-ready — no black boxes, no vendor lock-in. Track inventory the way engineers track code: with a clear history, explainable balances, and data you fully own. Get started for free and make write-downs, counts, and lender reports part of a clean, repeatable workflow.